Since Xenomorphs are the most popular adversary of Marines, here you can check out xenomorph mechanics more in-depth, with formulas and rules taken directly from the source code.

Also see: TGMC:Marine Mechanics

Contents 1 Health and Armor 1.1 Sunder 1.2 Critical 1.3 Plasma 2 Fire and resin 3 Pheromones 4 Queen mechanics 5 Buildings 6 Tier Slots 7 Larva spawn formula Health and Armor Regen is pretty complicated. It always works on weeds (or off weeds if you have CASTE_INNATE_HEALING), and changes according to several things:

Doesn't work if you're on fire. Base regen is 1+3.75% max HP. On resting weeds (white), regen increased 20% (after all modifiers, so it's always 1.2 times faster). But you only gain the bonus if you rest. When standing, a major debuff (modifier is 1.1 resting vs 0.2 standing, so about 5 times as slow). When you have Queen of Shrike alive (on same z-level) any regen is doubled. Pheromones increase regen by % of max HP or flat, depending on aura level. Formula:

REGEN = (1 + (maxHealth * (0.0375 + 0.01*Regen_aura_level))) * Multipliers * Ramp

Multipliers = (0.2*Standing + 1.1*Resting) * (1+Ruler_alive) * (1+Resting*Resting_weeds*0.2)

Regen works with a delay.

If under regen aura, delay is small. Ramp=1 Without aura, there is a 10 second delay to healing after taking damage. Then healing gradually increases from 0% to 100%. So it is worth resting for a while, but also note that timer starts working if you're standing up. So you can stand alert, wait for regen to ramp up, and then rest. Sunder regens a little different.

Activation of regen is under same rules. Base is 0.5% per tick. Resting doubles regen. Resting weeds double again. +10% per regen aura level. Sunder_regen = 0.5 * (1+resting) * (1+resting_weeds) * (1+0.1*Regen_aura_level)

Among other things, healing abilities (Psychic cure) also give 5% of HP restored to sunder heal.

Critical After getting smacked well enough, xeno goes to critical condition. He cannot perform actions, but still affected by regen mechanics. Also, off weeds he loses 5 health per tick.

Plasma Resting doubles regen Resting weeds give +20% Recovery aura does NOT affect plasma Fire and resin Fire turns off regen, auras and some abilities. Damage per tick is

(#fire_stacks + 3) * (1-fire_resist)

Resin jelly increases your fire resist by 20 flat, and protects you from obtaining new fire stacks. Existing fire stacks persist.

Using acid spit on xeno directly removes all fire from him.

Pheromones AURAS DO NOT STACK! Only the most powerful is taken for each pheromone.

Pheromones strength from lowest to highest

Drone Drone, Carrier Carrier, Defiler Defiler, Hivelord Hivelord and Shrike Shrike (they have the same pheromones strength), Tgmc hivemind materialisation.gif Hivemind, Praetorian Praetorian, Queen Queen, and finally King King.

Pheromones Effect TGMC Recovery.png Recovery Described above. Gives 1% regen per level. Also increases effect of healing abilities.

Regen only works on weeds.

TGMC Warding.png Warding Gives 2.5 Soft Armor (in each category) per level. TGMC Frenzy.png Frenzy +0.06 base speed per level. Aura_range = round(6+Aura_level*2)

Aura (pheromone) level (strength) is on each xeno's page. Varies from 2 to 6.

Queen mechanics Hive leaders have Queen's pheromones (type and level). And of course they can choose their own if they posses this ability.

Rally minions summons minions nearby, note that activation sets behaviour to “aggressive”. This patch Queen should get a rally point ability similar to that of Hive mind. Every minion will go there - including those who spawned after. Minions have low degree of independence, so if enemy is nearby they will aggro and attack.

Buildings Resin wall.png Resin wall. They regen on their own. Starts at 150 HP, regens at 3 HP per 5 secs, up to 300 HP. This maximum is same for all castes, starting health differs. Has 40% bullet resistance.

Resin door.png Resin Door. Has 100 HP for Drone with 1.5 Hardness and 160 HP for Hivelord with Hardness 2.

Before Containment SHitters are open, all weed costs only half as much.

Tier Slots Tier 4 are limited to one each of: Queen, Shrike, King.

Tier 3:

Tier 3 = (NUM_XENOS-NUM_TIER_3)/3+1

Minimum one. If current number of T3 is higher than that, no xeno is devolved (the number stays until death of one of them).

Tier 2:

Tier 3 = NUM_TIER_0+NUM_TIER_1+NUM_TIER_4 + 1 - NUM_TIER_3

So if somedoby evolves from T2 to T3, T2 slot is gone.

Tier 1 is unlimited

Tier 0 are larvas, see below.

Larva spawn formula Points are given each minute, as below:

PTS = ¹⁾ / (1+1.75)) * (1+Hijacked*2) + BUFF

So, taking BUFF as 0, with 1 silo you have multiplier of 2.75.

With 2 silos, you have multiplier of 3.75, which translates to 36% increase in larvas.

Buff base is 0. Updates once every 5 minutes.

Changes according to:

Monitoring decides that balance is off. There is a stalemate. If live players are less than ghosts. Then there is BUFF = GHOSTS * 0.75 For distress, you must gain 8 points per larva. Also, at the start you gain 2 burrowed larva.

When somebody enters the game on marine side, xeno gain 3.25 larva points. Therefore stable ratio is 2 xeno to 5 marines.